1. Technical Field
Embodiments consistent with the present invention are related to a method for transmitting digital audio data and, in particular, a method for transmitting digital audio data in a burst mode consistent with the jitter and bandwidth requirements of multi-format digital interface protocols.
2. Discussion of Related Art
Digital interface standards, such as High-Definition Multimedia Interface™ (HDMI), combine digital video and digital audio data streams into a single physical interface. By providing a single interface, connectivity between systems and devices using HDMI may be simplified because of the reduced number of physical connections. In addition, digital interface standards like HDMI may often provide higher bandwidth connections between devices compared to traditional analog audio/video connections. Accordingly, home entertainment components, gaming systems, personal computers, and portable consumer electronic devices have adopted HDMI interfaces to support the growing demand for access to high-bandwidth media-rich content.
Many of these devices utilize high-definition video and multi-channel digital audio standards to meet the bandwidth requirements to access the increasing availability of media-rich content. HDMI supports several of these standards. For example, HDMI transmits Advanced Television System Committee (ATSC) HDTV standards. In addition, HDMI audio support includes 8 channels up to 192 kHz, uncompressed digital audio, and compressed formats, including Dolby® Digital and DTS® and lossless digital audio formats Dolby® TrueHD and DTS-HD Master Audio™.
In operation, however, supporting multiple combinations of video and audio formats on a single interface can increase the complexity of the data transmission. An HMDI link, for example, can transmit one data type at any given time based on the active operating mode. For example, to transmit audio data, received audio sample data is processed into data packets, delayed, and transmitted when the video data period is inactive. This approach transforms continuous audio data received by the HDMI source encoder into a burst transmission received at the HDMI sink device.
At the HDMI sink device, the burst transmission of audio sample data may be buffered to reduce any noticeable audio problems resulting from the discontinuous data transmission. To minimize audio problems and to reduce the receive buffer size at the HDMI sink device, the HDMI standard has defined a maximum transmission jitter requirement for burst audio data samples. However, because the available audio bandwidth depends on the video format timing, changes to the audio data sample rate may negatively affect the jitter compliance of the transmitted audio data stream. In some cases, a user can configure the average number of audio samples for each audio sample packet transmitted across the HDMI link to meet the bandwidth and jitter requirements for a given video format timing. However, because HDMI is an intermediate interface, user configuration is not desirable nor does it necessarily ensure transmit jitter compliance for each audio sample rate corresponding to a particular video format timing. Accordingly, there is a need for an automated method to transmit audio sample data in a burst mode consistent with the jitter and audio bandwidth requirements of multi-format digital interfaces like HDMI.